Agatha H and the Airship City offered as free Amazon Kindle e-book

I just noticed that an e-book I reviewed here some time ago, Agatha H and the Airship City by Phil and Kaja Foglio, is currently being offered as a free Kindle e-book. (Barnes & Noble and Kobo do not appear to be following suit; the book is still $8.19 for the Nook or $7.69 for [...]